1. Field of the Invention
The present invention relates to a method and a computer program product for initializing a scanner to be used in an image processing apparatus, such as a multifunctional DPPC (i.e., Digital Plain Paper Copier), and more particularly to a method and a computer program product that can control the movement of the carriage of the scanner for performing the initializing process of the scanner in a short period of time.
2. Discussion of the Background
The recently developed DPPC may be configured such that power is supplied to the whole system of the DPPC by turning on the power switch. Further, the DPPC may be put in the shutdown state by stopping the power supply using a power key (e.g., a soft key), except some power may still be supplied to a monitoring part. In these types of DPPC""s, when the power switch is turned on or when a return operation from the shutdown state is performed, an initializing process of the scanner is performed. In the initializing process of the scanner, an automatic adjustment to the reading function of the scanner is made after the homing operation of the scanner is completed. An image reading device carried by the carriage reads a white plate arranged above the track of the carriage. The read image is then converted into an electric signal by an image sensor (i.e., generally, a CCD linear image sensor is used).
The automatic adjustment to the reading performance of the scanner is made based on the output electric signal. The output electric signal generated by reading the white plate includes various distortions caused by variations in the reading optical system, the lighting system, and the image sensor, etc. Therefore, shading data, for performing a correction in the analog signal process and the analog/digital conversion process, which are performed in the signal processing system of the image sensor, is acquired based on the detected value of the distortions. The automatic adjustment to the reading performance of the scanner is made based on the acquired shading data for correcting the variation in the sensitivity of the sensor (i.e., CCD sensor) and the uneven distribution of light of the lighting system.
In the scanner, the movement of the carriage which carries the reading device is controlled according to respective conditions when the initializing process is performed or when an image reading operation of the original document is performed. As illustrated in FIG. 14, the carriage is controlled to move in the forward or in the reverse directions within the home position sensor active (effective) range, the white plate active (effective) range, and the original document reading range. The three ranges are provided in order along the track of the carriage. In the home position sensor active (effective) range, the output of the home position sensor (i.e., HPS) to detect the position of the carriage is active (effective). In the white plate active (effective) range, the white plate is arranged and the white plate reading signal is active (effective).
In the initializing process of the scanner, the homing operation, which is performed based on the output of the HPS, and the reading operation of the white plate are performed. The white plate is provided between the HPS active (effective) range and the original document reading range.
The initializing process is described below referring to the flowchart in FIG. 15, which illustrates initializing process steps of the scanner when the power switch is turned on or when the return operation from the shutdown state is performed.
According to the steps, the carriage firstly moves in a forward direction for a predetermined distance to reach a position where the output of the HPS is apparently inactive (ineffective) at step S71. That is, the carriage moves toward the white plate or the original document side until it reaches the position where the output of the HPS is inactive (ineffective) after passing through the range where the output of the HPS is active (effective) wherever the carriage is positioned. Then, whether or not the output of the HPS is inactive (ineffective) is checked at step S72.
When it is determined that the output of the HPS is inactive (ineffective), whether or not the output of the HPS switches (changes) to be active (effective) from being inactive (ineffective) is checked at step S77 while moving the carriage in a minimal amount in a reverse direction at step S74. When it is determined that the output of the HPS switches (changes) to be active (effective), the position of the scanner is detected as the original position (i.e., a fiducial position) for the scanning operation at step S78 (i.e., a homing operation). When the output of the HPS does not switch (change) to be inactive (ineffective) even if the carriage is moved by the predetermined distance at step S72 (i.e., No at step S72) or when the output of the HPS does not switch (change) to be active (effective) even if the carriage is moved in the reverse direction within the allowable range at step 74 (i.e., No at step S75), it is determined that the scanner malfunctions. Error processes, for example, to stop the operation, are performed at steps S73 and S76.
The carriage then moves in the forward direction for a predetermined distance at step S79 from the detected original position to reach a position where the white plate is read. An automatic adjustment to the reading performance of the scanner is made at step S80 based on the read value of the white plate. When the adjustment is made, the carriage moves for a predetermined distance in the reverse direction to a standby position (i.e., original position) at step S81. The scanner is put into the standby state at step S82. The process is then finished.
The initializing process operation performed according to the above-described processing steps is further explained referring to timing diagrams in FIGS. 16 through 18 which show the mutual relationship between the position of the carriage and the output of the HPS.
The timing diagrams in FIGS. 16 through 18 illustrate that the carriage is located in a different position at power-on time. In FIG. 16, the position of the carriage is shifted to the side of the white plate with respect to the switching (changing) point of the output of the HPS. In FIG. 17, the carriage is positioned close to the switching (changing) point of the output of the HPS. In FIG. 18, the position of the carriage is shifted to the side of the physical restrictive position with respect to the switching (changing) point of the output of the HPS. According to these examples of the present invention, a sensor having a hysteresis property in which the switching (changing) point of the output differs according to the moving direction is used as the HPS to detect active (effective) and inactive (ineffective) positions. The original position of the carriage is then detected when the output of the sensor switches (changes) to be active (effective) from being inactive (ineffective) while the carriage moves in the reverse direction.
In any of these examples shown in FIGS. 16 through 18, the homing operation is started after the carriage moves in the forward direction for a predetermined distance to reach the position where the output of the HPS is apparently inactive (ineffective). That is, the original position of the scanner for the scanning operation is detected when the output of the HPS switches (changes) to be active (effective) from being inactive (ineffective) while the carriage moves in the reverse direction. Therefore, the example shown in FIG. 16 (i.e., when the position of the carriage is shifted to the side of the white plate with respect to the switching (changing) point of the output of the HPS) requires the longest poriod of time for detecting the original position of the scanner among the examples shown in FIGS. 16 through 18. The same operation is performed in any of the examples shown in FIGS. 16 through 18 until the scanner is put in the standby state after the initializing process including the detection of the original position of the scanner and the automatic adjustment to the reading performance of the scanner is completed. Thus, the example shown in FIG. 16 requires the longest period of time for return (change) operation from the shutdown state.
The initializing process of the scanner is thus performed by controlling the movement of the carriage as described above when the power switch is turned on or when the return operation from the shutdown state is performed. Generally, this initializing processing operation is directly controlled by the control section of the main body of the DPPC. FIG. 19 is a block diagram illustrating an example of the system for controlling the initializing process of the scanner. An output of the HPS 26 is input to the main body control CPU 30. The main body control CPU 30 directly controls the motor driver 24 for the scanner motor 21. The main body control CPU 30 controls each component of the DPPC including the image processing section 31 which processes read image data.
Therefore, the initializing process of the scanner, which is executed when the power switch is turned on or when the return operation from the shutdown state is performed, is performed based on a program of the main body. Because the initializing process of the scanner is performed after the initialing process of the main body is completed, a relatively long period of time is required before the scanner is put in the standby state.
This initializing process of the scanner may be performed by controlling the movement of the carriage independently. FIG. 20 is a block diagram illustrating an example of the system for controlling the movement of the carriage independently. The output of the HPS 26 is input to the scanner control CPU 25. The scanner control CPU 25 controls the motor driver 24 for the scanner motor 21 independently of the main body control CPU 30. According to this system, the homing operation of the scanner is performed without waiting the completion of the initializing process of the main body, thereby reducing the time required to initialize the scanner.
Conventionally, the time required to perform the initializing process of the scanner, such as the homing operation and the automatic adjustment is longer than the time required to warm-up the main body. Therefore, the time required to initialize the scanner is not an important factor in the amount of time required to place the DPPC in the operational state (i.e., in the startup time).
However, considerable efforts are being put into reducing the startup time of the DPPC. As a result, the time required for the warm-up process of the main body has drastically been shortened. Therefore, the time required to initialize the scanner is an important factor in the amount of time required to put the DPPC in the operational state.
The present invention has been made in view of the above-mentioned and other problems and addresses the above-discussed and other problems.
The present invention advantageously provides a novel image processing apparatus, method, and computer program product that can perform the initializing process of the scanner in a short period of time.
According to an example of the present invention, the image processing apparatus includes a carriage configured to carry an image reading device, a white plate configured to be read by the image reading device for adjusting a reading level of the image reading device, a home position sensor configured to detect the position of the carriage, and a controller configured to control the movement of the carriage. The controller moves the carriage based on the output of the home position sensor to perform an initializing process of the image reading device including a homing operation and a white plate reading operation.